The United States and Japan will step up their defence cooperation to deal with the threat from nuclear-armed North Korea as tensions in East Asia remain high, officials from the two allies said on Thursday.

Woolies breached shopper docket agreement

Motorists will still be able to get big fuel discounts by combining supermarket and petrol fuel discounts offered by retail giants Coles and Woolworths, a court has found.

The Australian Competition and Consumer Commission (ACCC) had argued that a Coles petrol discount of 14 cents breached undertakings the company had agreed with the consumer watchdog.

The undertaking prevented Coles from offering a discount of more than four cents, when it was contingent on a supermarket purchase.

But Justice Alan Robertson on Monday found that Coles' 14 cent discount was not in breach of that agreement.

He said that although the total discount that customers were able to get at the fuel pump was well above the four cents, the full offer was not linked to supermarket purchases.

"In my opinion, four cents per litre of the offer only was contingent on supermarket purchases and 10 cents per litre of the offer only was contingent on an acquisition of goods or services from Coles Express," he said.

ACCC Chairman Rod Sims said he was disappointed by the decision.

"We will carefully consider the judgment and its implications for competition in fuel markets and any detrimental price impact on fuel consumers," he said.

Justice Robertson did, however, find that Woolworths had breached the ACCC undertakings in its eight cents discount.

Customers were able to obtain an eight cent per litre discount on fuel if they spent at least $30 in a Woolworths supermarket as well as $5 or more at a petrol station.

The consumer watchdog had argued this was in breach of its undertaking with the retailer because the discount was only available to customers who made a supermarket purchase.

A Woolworths spokeswoman welcomed the decision, saying it provided it with clarity.

"We said at the time when we sought a declaration from the Federal Court that we accepted we needed to make our discounts independent of each other, and this change was implemented some time ago," she said in a statement.